The present disclosure relates generally to the field of navigation. More specifically, the present disclosure relates to a system for and method of navigation using weather radar.
Required navigation performance (RNP) specifications for Federal Aviation Administration (FAA) approach procedures require accurate navigation performance. Conventional aircraft often rely on a Global Positioning System (GPS) and Inertial Navigation System (INS) to estimate the aircraft's position (latitude, longitude and altitude) and other flight parameters (e.g., track angle, ground speed, pitch, roll, heading, angular rates and accelerations). In addition, the RNP specifications require redundancy for navigation sources in case of a GPS or other sensor/system outage. In general, conventional systems rely upon an INS and accompanying sensors to provide redundant parameters for navigation. The INS itself is expensive. Sensors for an INS generally must be avionic grade and can also add significant cost. An INS system and associated sensors also increase the weight of the aircraft.
Therefore, there is a need for a system and method that can assist navigation at a low cost and still meet RNP requirements. There is also a need for a system for and a method of determining accurate position to maintain navigation that meets the RNP requirement. Further still, there is a need for a system and method that can determine accurate heading angle, track angle, ground speed and/or other flight parameters that provides continuity in the event of GPS source outage. In case of a GPS outage, aircraft position, track angle and ground speed are no longer provided by the GPS, therefore these parameters have to be provided by another aircraft system. Generally an INS is used to extrapolate the current position using track angle and ground speed that is estimated from integrating angular rates and accelerations that the INS measures. So further still, there is a need for a low cost system and method of determining track angle and ground speed that can be used to extrapolate the current position.
The heading reference from a low cost AHRS does not always meet the accuracy requirements for the heading reference. Therefore still further, there is a need for a system and method that determines accurate heading angle.
Yet further, there is a need for a system and method that determines heading angle, track angle, and ground speed without the addition of significant equipment. Further still, there is a need for a low cost, light weight replacement for an INS or for equipment that estimates accurate heading angle, track angle and ground speed.